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在远距离内输电线路中串入固定电容器,可能会引起次同步谐振(SSR),为此,在串补系统中使用了基于电压源换流器(VSC)的新一代串联补偿装置静止同步串联补偿器(SSSC)来替代部分固定电容器。首先分析了SSSC基本运行原理,通过对VSC输出电压幅值和相位的控制,使SSSC能够向线路中注入串联的容性电压,相当于提供了串联补偿电容。分析了不同容量SSSC的电气阻尼特性,针对SSSC原有控制抑制次同步谐振效果不佳的缺点,设计了SSSC次同步谐振多模式阻尼控制器。通过通带内低相移的扭振模式带通滤波器滤出系统每个扭振模式信号后再进行相位补偿,使SSSC能够在所有扭振频率附近提供正的电气阻尼。基于测试系统的频域和时域仿真结果表明,简单地增加SSSC的容量并不能有效地化解系统发生次同步谐振的风险,所设计的多模式阻尼控制器不仅能够阻止发电机和串补线路之间次同步谐振的产生,并且能有效地减小所需SSSC装置的容量。
In the long-distance transmission line fixed capacitor stringing may cause subsynchronous resonance (SSR), therefore, in the series compensation system based on voltage source converter (VSC) based on a new generation of series compensation device static synchronous series Compensator (SSSC) to replace part of the fixed capacitor. Firstly, the basic operating principle of SSSC is analyzed. By controlling the amplitude and phase of the VSC output voltage, SSSC can inject a series capacitive voltage into the line, which is equivalent to providing a series compensation capacitor. The electrical damping characteristics of SSSC with different capacities were analyzed. In view of the shortcomings of SSSC original control suppression subsynchronous resonance, the SSSC subsynchronous resonance multi-mode damping controller was designed. Phase-compensated for each torsional mode signal in the system by a torsion-mode band-pass filter with low phase shift in the passband, enabling the SSSC to provide positive electrical damping near all torsional vibration frequencies. The results of frequency domain and time domain simulation based on the test system show that simply increasing the SSSC capacity can not effectively mitigate the risk of subsynchronous resonance. The designed multi-mode damping controller can not only prevent the generator and series compensation The generation of subsynchronous resonance, and the capacity of the SSSC device required can be effectively reduced.